there is a readymade base tile, it has a cove shape where it meats the floor tile annd a clean edge at the top to continue with wall tile, or end and paint the wall.

Look... or ask if there base tile that matches or compliments your tile of choice. It makes for a great finish. They generally are not 5" in height, but tiles vary, get all your tiles ready before you get started.

Thanks @Lyn Nielson do you have a link to what you're referring to? I was planning to use the same floor tile for the baseboard, so he'll just cut it to the size I want. He's almost done finishing the floor and asked me what height I want for the tile baseboard. I was thinking about 4" h?

this is a corner tile. the photo didn't attach... google Lowes.com and ask for cove tile ... schluter brand has a few options, so does American Olean. I'll keep trying to add the photo.

I need to see the bathroom to have any idea about baseboard . if this is already planned then 4" is perfect nad I like the idea of the same tile to line up with the floor and use schluter for the top edge in a stainless color it will just give aclean edge andd not really be noticeacble then just silicone where the tile meets the floor. You could do it on top and bottom like this but if the tile setter is good that cut side will be perfect and the silicone is all you need.

The question you need to ask is if he cuts a piece to make a baseboard, what is the exposed edge going to look like? Everyone's definition of what a finished edge may be different. That is why tile made for this purpose was recommended by Lyn.

I am going to be using “classic grey” schluter edge to match our light grey tiles